Cutout for electric lamps



I. H. VAN HORN C UTOUT FOR ELECTRIC LAMPS Dec. 14-, 1943.

Filed May 24, 1945 Fig; 1.

lnven'tor Irvin H. VanHor'n,

, by His A+Torne9 Patented Dec. 14, 1943 CUTOUT FOR ELECTRIC LAB/[PSIrving H. Van Horn, East Cleveland, Ohio, assigner to General ElectricCompany, a corporation of New York Application May 24, 1943, Serial No.488,197

Claims. (01. 315-75) My invention relates in general to series electricincandescent lamps and other similar electrical devices comprising afilament or other electric energy translation element mounted in a glassenclosure such as a bulb. More particularly, my invention relates tocutouts for such series lamps and devices which operate to preserve theelectrical circuit through the lamp. or device, upon failure of thefilament or other element thereof, so that the other devices in theseries circuit will continue to operate.

Cutout constructions for series lamps have been proposed heretofore inwhich the inner lamp leads are formed with closely spaced portions whichare bridged by a film cut out element. With such a cutout construction,when the lamp filament fails during operatioman are usually formsbetween one end of the broken filament and one of the inner leads. Sucharc then melts back the said inner lead in the form of a ball untileither the ball contacts the other inner lead so as to short-circuit thelead-in wires, or until the heat of the arc is suificient to break downthe insulating film on the cutout element.

Occasionally, however, such cutout constructions fail to operate in theintended manner. Thus, under certain conditions of service which maydevelop after failure of the lamp filament, an arc may form between theclosely spaced portions of the lead-in wires which arc, because of thesmall arc gap and therefore the small amount of wattage involved,posseses insufiicient heat to effect the breakdown of the insulatingfilm on the cutout element with the result that the arc continues topersist. Because of the inherent tendency of arcs to wander, thepersisting arc may then travel past or beyond the cutout element to apoint intermediate the cutout and the stem press where the arc gap is ofgreater length, as a result of which the arc may then possess sufiicientheat to melt away one or the other of the lead-in wires at a pointbetween the stem press and the cut-out and thus render the cutoutstructure wholly inoperative. The arc may then continue down into thestem press and lamp socket, resulting in extinguishment of the circuitand possibly a damaged socket.

One object of my invention is to provide a cutout for an electric lampor similar :device which is simple in construction and positive inoperation.

Another object of my invention is to provide a cut-out construction foran electric lamp or similar device which will operate to preserve theelectrical circuit through the lamp, upon failure of the filamentthereof, 'under' practically all conditions which may develop within thelamp.

Still another object of my invention is to provide, for an electric lampor similar device, a cutout construction of positive operatingcharacteristics which does not require the forming of the inner lamplead-in wires to a special shape. A further object of my'invention is toprovide a cutout construction for an electric lamp or similar devicewhich is capable of supporting an arc, and thus preserving theelectrical circuit through the lamp, for an indefinite period of time. I7

Further objects and advantages of my invention will appear fromthefollowing description of a species thereof and from the accompanyingdrawing in which: i

Fig. 1 is a front elevation of an electric incandescent lamp providedwith a cutout structure according to my invention; Fig. 2 is a plan Viewon an enlarged scale of the cutout structure of the lamp shown in Fig.1; Fig. -3 is a vertical section on the line 3-3 of Fig. 2; and Fig. 4is a perspective view of the cutout structure-comprising my invention. i

Referring to the drawing, the electric incandescent lamp there showncomprises a glass bulb it having a base H secured thereto and a mountstructure 12 sealed therein. The said mount structure comprises are-entrant glass stem I3 having-a press portion I4, a pair of lead-inwires l5, l5 sealed in the press portion M of the stem and connected tothe terminals of the base H, and an electric energy translation elementor filament it connected to'the inner ends of the lead-in wires I5. Theinner portions ll of the lead-in wires, immediately inward of the stempress l4, extend more orless parallel to one another and are spaced theusual distance apart (in the lamp shown, around i% or thereabouts). I a1 Mounted on theinner leads ll, immediately adjacent the stem press I4,is a cutout structure I8 according to theinvention. The said cutoutstructure comprises a pair of like "metal holder clips or stampingsl9formed from suit able strip material andsecurely fastened tothe innerleads IT, at opposite points thereon, with their flat or planar surfacesextending vertically. For this purpose, one-end of each stamping" I9 isformed with" a vertically-extending loop or eye portion 20 which extendsthe-full "vertical length of the stamping'and which is pinched tightlyaround the inner lead I! to thereby securely fasten 'the stamping orclip in place on the said inner lead. The other end of each stamping I9is notched, as indicated at 2|, to provide an extension or ear 22 ofreduced vertical extent. The stampings or clips iii are mounted on theinner leads 11, one in aninverted position with respect ,tothe other, soas to vertically space the extensions, oneabove the other, a"slightdistance apart such as, for instance, inch or thereabouts.

Carried by. the metal holder clips l9 and conwidth with the ears orextensions 22 thereof necting the extensions 22 thereon is a film-type 1cutout element 23 preferably in the form of a short length of aluminumwire having a coating 24 of aluminum oxide extending over at least aportion of its length, preferably over the upper half or so as shown inthe drawing. The insulating film or coating 24 is of such a character aswill not break down at or somewhat'above the operatingvoltage. of theindividual lamp elements in the series, but. which will. break down ata. voltage appreciably above the operating voltage of .theindividuallamp. elements, such as the; fullline voltage across the. seriescircuit.

Thus, where. a. group of twenty. lamps designed to operate. atj..30.volts. are connected in. series acrossa. GOD-volt. current supply, theinsulating V .film 24 on the cutout element. 23 is preferably of. sucha. character as. will not break down below 40 volts or thereabouts Thecutout element 23. may be. fastened in place. on themetal clips. I inany suitable man; ner which will. insure. theinsulation. of the innerleads I"! from one another by the oxide. coating Zionthe. cutoutelement.Preferably, however, the; free. endslofth'e ears. or extensions 22 ontheclips I19 are .formedinto. loops. or. .eyes which are verticallyvalignedgwith. one another. -The..wire cutout .elementnZB. extends.through the. eyes. 25,..and. the-saidseyes. arepinched or closed aroundthe wire..element, to. thereby securelyfasten, the. latter in. placewithin the metal clips. l9. The;-wire .cutout element 23.. is preferablydisposedtwithin the. aligned loops. or eyes. 2,5..withthe. coated endportion 24; thereof positioned within one of the. eyes and .thebare 0.1:uncoatedend thereof. positioned ,withi'nthe other of said. eyes...Onlythe eye 25. enclosing theiuncoated end of the. wire .cutout.elementis pinchedtightly thereonto to hold the wire. element in place flwithin.themetal clips [9; The other eye 25, enclosing. the. coated end of thewire cutout elementis. merely closed loosely therearoundso. asnot. to.scratch. or otherwise injurezthe oxidecoating 24. and thus cause apremature breakdown 0f...the cutout.

To enable the application. of. the cutout structure l8. to. lampsprovided with. a glass arbor. extending inwardly. from the stem press Htbetween: the. inner leads I], and further, to

compensate for variations in the spacing. of the inner leads I! ofdifferent lamps, those'piortions of. the metal clips-l9. between theinner leads .I'!

are preferablyoffset laterally from the plane of the. inner leads, as bybending. the metalclips or stampings. I9 into. amodifiedJZ-shape as.viewed in plan. (Fig. 2);. Such lateral. offsetting of the clips ,l9thus provides clearance for the glass arbor with. which. the lamp may beprovided.

The metal c1ips,l.9;should;beof such, propor tions and of such;material. as to readilysupport for an indefinite period. of time,without melting, any are that, may ,form therebetweenduring lam seryice.In otlienwords, the. meta1i 1ips around or so in width.

. In operation, the cutout I8 will not function as long as the filamentIt remains intact, inasmuch as thesoxide film 24 on the cutout element.23 acts as an insulator at the normal operating voltage of the lamp.However, ifthe filament I6 fails when cold (i. e., when the lamp isnotin operation), the cutout element 23 then operates when the circuitswitch is subsequently closed. The fullivoltage of the line being thenimpressed across. the film cutout element 23, the insulatingfilm 24thereon is punctured and a conductive path thus provided between theleadin' wires l5, 15. This allows the other lamps of the-series to lightup and at the same time shows up the defective lamp.

Should the filament l-fi fail when hot (i. e., during operationof thelamp), an are forms between the broken filament and one or the other ofthe inner leads [1. This are then melts the said inner lead back inthe-formof a molten ball as aresult of which the arc travels down to thecutout structure it and effects, in the great majority of cases, thebreakdown of the insulating film 24 on the cutout element 23. In theevent the arc should. fail to so break down the insulating film 24' onthe cutout element 23, the arc will. then persist between the metalclips I9, particularly between. the closely adjacent loops or eyes 25 ofthe said clips. Because of the adequate heat-dissipating capacity of themetal clips, however, the-said clips. will therefore support thearctherebetweeh for an indefinite period of time without melting orbecoming otherwise damaged. Furthermorebecause of the. relativecloseness to one another of tlie'eyes 25 on the metal clips. IS, the.arc: will. tendto persist therebetween rather than travel. down or pastthe 'cutout. structure i8. and: onto: those exposed portions of th innerleads I? intermediate the stem press M. and. the metal. clips. H]: whereitmight melt. away one or the. other of the inner leads Hat such pointand thus render the cutout structure 18:.who1ly inoperative. To furthergu'ardagainst such. acondition arising,the metal clips. I9 are; mounted,'onthe inner leads [-1 as close. as. possible to. the stem press I 4 so.as to leave as. little as: possible of. the inner leads ex:- posedbetween the stem press! landl the. metal clips.,|9.. The; lateraloifsettin'glof the metal clips l9 between the. inner leads l'l: is ofparticular utility in. this connection inasmuch as it: per mits themeta-lv clips. to be mounted on the inner leads below the top or crown:26- (Fig; 3) ofthe stem press l4: and immediately adjacent the point onthefstem press where the said: leads extend therefrom. so that therearevery little, i'f a'ny, exposed sections of the inner leads intermediatethe stein press and. the metal? clips ill to which sectionsthe arccanstrike. 7 .What Iclaim as new and desire to secureby Letters Patent ofthe United States is: 1'. An electric. incandescent lamp comprising abulb;:a:.fi1ament.disposed within said bulb, a p'air of lead-in wiresextending into said bulb and connected to said filament, a pair of metalholders secured one to each of said lead-in wires and having portionsclosely spaced from one another, and a film cutout element carried bysaid holders and in contact therewith, said holders being constructedand arranged to support, for an indefinite period of time withoutmelting, any are that may form within the lamp during service uponfailure of the filament thereof.

2. An electric incandescent lamp comprising bulb having a re-entrantstem provided with press portion, a filament disposed within sai bulb, apair of lead-in wires sealed in the stem press and having inner leadportions extending into th bulb from the said stem press and connectedto said filament, a pair of metal holders secured one to each of saidinner leads at points thereon as close as possible to said stem pressand having portions closely spaced from one another, and a film cutoutelement carried by said holders and in contact therewith, said holdersbeing constructed and arranged to support, for an indefinite period oftime without melting, any are that may form Within the lamp duringservice upon failure of the filament thereof.

3. An electric incandescent lamp comprising a bulb having a re-entrantstern provided with a press portion, a filament disposed within saidbulb, a pair of lead-in Wires sealed in the stem press and having innerlead portions extending into the bulb from the said stem press andconnected to said filament, a pair of metal holders secured to andenclosing appreciable lengths of said inner leads immediately adjacentsaid stem press and having portions closely spaced from one another, anda film cutout element carried by said holders and in contact therewith,said holders being constructed and arranged to support, for anindefinite period of time without melting, any are that may form withinthe lamp during service upon failure of the filament thereof.

4. An electric incandescent lamp comprising a bulb, a filament disposedwithin said bulb, a pair of lead-in wires extending into said bulb andhaving inner lead portions connected to said filament, a pair ofstrip-like metal holders of appreciable width secured one to each of andalong said inner leads and having extensions closely spaced from oneanother and provided with aligned loops, and a film cutout elementextending through and in contact with said loops, at least one of saidloops being pinched tightly around said cutout element to therebysupport said cutout element in place within said loops.

5. An electric incandescent lamp comprising a bulb, a filament disposedwithin said bulb, a pair of lead-in wires extending into said bulb andhaving inner lead portions connected to said filament, a pair ofstrip-like metal holders of appreciable width secured one to each of andalong said inner leads and having extensions closely spaced from oneanother and provided with aligned loops, and a film cutout elementcarried by and in contact with said holders, said cutout elementcomprising an elongated body of aluminum extending through and incontact with said loops, the portion of said cutout element within oneof said loops having a coating of aluminum oxide thereon and the portionof said cutout element within the other of said loops being free of suchcoating, said one loop being only loosely clamped and said other loopbeing tightly clamped around the cutout element.

IRVING H. VAN HORN.

